Recently, infectious diseases caused by viruses, such as Ebola hemorrhagic fever and dengue fever, have been rapidly widespread in the world and grown into social issues. To prevent a pandemic, for example, appropriate isolation of a patient after the onset of symptoms is very important. Furthermore, a patient who is infected but free of symptoms needs to be properly determined to prevent the diffusion of the virus because of the patient. This prevention will be also important in the future.
The existing detection method using immunochromatography is an effective method since results can be obtained relatively in a short time at very low cost. However, the detection sensitivity is insufficient in this method even if an antibody against a virus which is the substance to be measured has been developed. In addition, the target substance cannot be detected in a state where the amount of virus is small before the onset of symptoms.
If a genetic test is conducted, at least the problem in which the target substance is not detected due to the lack of detection sensitivity can be solved. However, in a genetic test, the detection device and the reagent are expensive, and further, the inspection takes a long time.
To solve this problem, a method for identifying a virus using a nanopore is known. This method employs marker particles whose periphery is modified by an antibody specifically identifying and bound with a virus. Each marker particles is larger than each virus. Even in the early phase of infection in which the amount of virus is small, the marker particles are bound with a virus in the order of a marker particle, a virus and a marker particle. In this manner, a composite particle is formed. If the waveform of the ion current is observed when the composite particle passes through a nanopore, the waveform of the current drop signal indicates a double-peaked shape. Thus, a virus can be specifically identified. As a result, viruses can be detected one by one. The detection can be performed with high sensitivity.
However, the composite particle needs to pass through the nanopore in the order of a marker particle, a virus and a marker particle to be to be capable of observing the double-peaked waveform. Thus, the passage attitude of composite particles is restricted.